Process of separating solid matter from a liquid



Feb. 28,1939. c. w. GORDON PROCESS OF SEPARATING SOLID MATTER FROM ALIQUID 1 Filed Nov. 27, 1936 ik'fmrdoli a. w. M

ATTORNEY INVENTOR llzarles BY Patented F eb. 28, 1939 PROCESS OFSEPARATING SOLID MATTER FROM A LIQUID Charles W. Gordon, Munster, Ind.,assignor, by mesne assignments, to Combustion Engineering Company, Inc.,a corporation of Delaware Application November 27, 1936, Serial No.113,023

g 4 Claims. 7 (01.100-38) I The present improvement relates to the artof I "'-"screening'solid materials, carried in suspension in a liquid,out of such liquid and forcing further liquid out of the-screenedsolids, or tails", by

' meansof a press, and is more particularly c-once'rned with cases wherethe solids carried in suspension are of varying sizes including veryfine particles. A typical instance of this sort is -'that of distilleryslop;

1o When-such assorted sizes of materials are to be screened out of aliquid, it is found at once that to common the process at a reasonablespeed and in such a way that the filtered material comes from the,filter without excessive moisture, it is practically necessary to filterthrough two or more screensofdifferent number of mesh. A practicalinstallation, may for example use two screens, the slopv being fed inthe first place on a 30 mesh per inch screen, the effluent from thisfilter being run on .to'a filter of 200 mesh per inch. If a single 200mesh filter were used and all of the slop :fed directly to it, theaction would be slowed up very much and-the material screened out wouldcome from the filter very much wetter than when the two mesh filterreferred to is used. The reason for thisis that in the former case thefine material is intimately mingled with the coarser material, closingup the interstices between the coarser particles so that the drainagethrough the mass is nearly as slow as if the whole mass were made up offine particles. If however'the coarser particles are filtered out first,then the drainage through this portion of the mass is very much morerapid and thorough, and the portion of the 5 mass in which thefiltration is slow and not very thorough is reduced to a minimum. Thetotal moisture retained by the two masses is as a consequence muchsmaller than with a single fine mesh filter. In the case. of distilleryslops, the 40 relative proportions of the two masses will be, forexample, as follows: The 30 mesh screen may retainapproximately 10 lbs.of wetfiltrate per bushel of slop processed and the 200 mesh screen mayretain approximately 2 lbs, the ratio thus being 5 to 1.

The moisture content of the filtrate is in any case such that a greatportion of it can be removed by a suitable press. If, as is regularpractice, the filtrate from the 30 mesh filter is mingled with that fromthe 200 mesh and the resulting mixture put through a press, it is'foundthat the effluent carries an entirely too large proportion of the fineswith it.

The object of the present invention is to remedy this condition byproviding a novel process and apparatus for treating the wet materialcoming from the filter. When this novel process is used, it will befound that in addition to reducing the amount of fine material carriedofi by the 'efiluent a further benefit results which is that a 5 muchdrier. solid product from the press can be obtained than could beobtained from such a pressing operation as practiced heretofore.

The invention is illustrated in, and will be discussed in connectionwith, the drawing on the 10 single sheet filed herewith in which Fig. 1shows a lateral elevation, partly in section, of aninstallationutilizingthe improved process and apparatus. Fig. 2 is a sectionalview on line2--2 of Fig. 1- p and. Fig. 3 is a sectional view on line 3-3 of Fig. 1.15

The material to-be treated is fed to the filter through the spout I. Itfalls on the 30 mesh screen 2 where a substantial part of the solid par-.ticles are retained. As mentioned above, this may be about to of thetotal. The water flowing through the screen and carrying the finerparticles with it falls upon the 200 mesh screen 3. This retains all ofthe suspended solids left whichv it is practically advisable to filterout. The emuent falls to the bottom of the screen housing and 25 flowsdown-to the outlet trough 4.

The typeof screen illustrated in the drawing *is a well known commercialtype which gives a horizontal rotary motion to one end of the screen,the power being furnished by a motor 6. 'The mechanism for giving thismotion is indicated at 8. The opposite end lot the screen is guided togive this end a reciprocating movement. The screen is inclined and thewhole arrangement is such that the material caught on screens 2 and 35 3is gradually fed down toward the lower or left end and is discharged atH and I2 respectively. The particular type of screen or its action arenot per se apart of the present invention and any device that separatesthe grain as indicated will 40 answer the purpose.

The press itself which I utilize is likewise of a commercially availabletype. It may briefly be described as follows: Within the casing 55 twodiscs I4--l4 are mounted to rotatabout their 5 axes Iii-l6, being drivenby means of the circumferentially arranged gear teeth Ill-l8 engagingthe spur gears 20. These spur gears are each mounted on an axle 22, andon each axle 22 there is mounted a gear wheel 24, which are driv- 50 enby the spur gear 26. These spur gears 26-26 are mounted on shaft 28,which is driven by any suitable means.

It will be noted that the axes l6-l 6 are inclined away from thehorizontal in opposite directions 5 and that the faces 30 of the discsll are frustoconical. Each surface 30 is perforated as indicated at 32and has mounted on it a perforated plate 34. This in turn has mounted onit a screen cloth 36. The openings in the disc 30 and in the plate 34are fairly large and readily allow anything to flow away through themwhich is passed by the screen cloth 36. The screen cloth has rather fineperforations, these being in practice about a millimeter in diameter.

It will be noted that the two conical surfaces are very close to eachother and that elements of the opposed portions of the conical surfacesare parallel to each other in the region vertically below the center anddiverge at the region directly above the center. At intermediate pointsthey approach each other more and more closely as the lowest point isapproached,

This press is, as stated, a commercially available one and operatesbriefly as follows: Material to be pressed is fed in from above and atone side of the axes Ill-l8. As the discs are rotated. this material iscarried downward toward the lowest point, the space available for itbecoming more and more restricted, with the result that its moisture ispressed out through the cloth. This moisture then leaves through theperforations .in the plates and flows downward and is discharged at 40.

Under prior practice the material from the 30 mesh and that from the 200mesh screens were fed into the press together and mingled, with theresult, pointed out above, that a great proportion of the fines waspressed out through the screen cloth.

The perforations through the screen cloth are of such size that thescreen cloth retains substantially all of the coarser material butrather readily passes material of the size caught by the 200 meshfilter. The perforations cannot be made smaller without seriouslyinterfering with the flow of the liquid through the cloth.

By my improved device and in accordance with my improved process I feedthe fine material into the press in such a manner that it is surroundedby coarser material on all sides. From Figs. 1 and 2, for example, itwill be clear that the fine material from I2 falls into thefunnel-shaped entrance 42 which delivers it through the channel 44 tothe press, surrounded on three sides at 48, 48 and 60 by coarsermaterial from the 30 mesh filter 2 coming in through the spout I l. Thefourth side need not be closed in with the coarser material in thisparticular press, as the material here does not lie against screencloth, but against the solid hub 3|. As a result the fine materialnowhere comes in contact with the screen cloth 36, through which itmight pass. Particles of this fine mass may be carried a little distanceinto the coarser material but will be caught by such coarser materialand held and kept from reaching and penetrating this screen cloth.

Inasmuch as the finer material is prevented from reaching the screencloth and from being carried along by the liquid which has been pressedout and forced through-the screen cloth, it is now found that a muchhigher pressure can be applied in the press. Another factor enters hereto make the application of higher pressures possible-when the presentprocess is used. It is possible to apply pressure to masses of suchgranular material generally only because there is frictional resistanceto movement of the particles over each other. The more of thisfrictional resistance exists, the higher the pressures that can beapplied. Now the very fine particles where they are present act in thenature of a lubricant and by segregating them and putting them in thecentral area, this lubricating action is removed. With the presentprocess the pressure may be raised from 50 to 60 pounds per square inchto 125. The cake coming from the press is therefore very much drier andthis is a great advantage when the material is to be dried further, asis usually the case, such further drying being performed by evaporationand therefore being relatively expensive.

The nature of the invention will be clear from the above and it will belikewise clear that the application of the inventive idea is not limitedto any particular form or type of press. In fact, the invention canobviously be used equally well in connection with a centrifuge. All thatis required to take advantage of the invention is that the coarsermaterial from the 30 mesh screen be interposed between the mass of finerparticles and every surface by which the moistui-e forced out leaves thepress.

While I have described the invention in the above with particularreference to distillery slops and have mentioned particular sizes ofparticles, filter screens and press screens, it will be understood thatthis is not intended in any way as a limitation but merely by way ofillustration. It will likewise be obvious that many variations can bemade in the particular apparatus described without departing from theinventive thought.

What I claim is:

l. The process of removing liquid from wet granular material comprisingthe steps of draining the free inter-granular liquid oil from thematerial, separating the material into two portions, one of whichcontains substantially all the grains below a predetermined size and theother of which contains all the remaining grains, placing a layer of thelatter portion in contact with the screen of a press, placing the formerportion on said layer, and pressing further liquid other thanintergranular liquid out of the material by mechanically pressing thetwo layers against the press screen with considerable force. 4

2. The process of removing liquid from wet granular material comprisingthe steps of draining the free inter-granular liquid off from thematerial, separating the material into two portions one of whichcontains substantially all the grains below a predetermined size and theother of which contains all the remaining grains, feeding the materialto a press in such a manner that the former portion is everywhereseparated by a layer of the latter portion from the surfaces of thepress through which the liquid flows which is forced out by the press,and applying relatively great pressure by the press to the material,thereby pressing out of the mass any residual intergranular liquid andfurtherliquid from within the grains.

3. The process of removing liquid from wet granular material comprisingthe steps of draining.the free inter-granular liquid off from thematerial, separating the material into two portions one of whichcontains substantially all the grains below a predetermined size and theother of which contains all the remaining grains, feeding the materialtoa. press in a stream of which the former portion forms a core surroundedby an enveloping layer of the latter portion, and exerting relativelygreat pressure on the mass,

whereby there is removed any residual intergranular liquid and furtherliquid from within' the grains.

a predetermined size and the other of which coninto a pressing-devicehaving screen surfaces with openings through which grains below saidsize could pass but through which substantially no grains above saidsize can pass, the material beingied in so that a layer of the secondportion everywhere separates the first portion from the screen surface,and forcing the material toward the screen surface with relatively greatforce.

l0 talus all the remaining grains, ieedinzthe two CHARLES W. GORDON, 10

